This invention relates to cutting of roof rafters, and, more specifically, to a template and tape to facilitate the measurement and cutting of all necessary rafters for a sloping roof given the desired pitch and a zero pitch rafter plan.
Traditionally, a carpenter cuts out the rafters for a structure using a framing square, a carpenter's tape, a look-up table for the desired pitch from any of several available rafter books, and the zero pitch roof plan (see FIG. 1) from which the run of each rafter is given or can be obtained by measuring the drawing. This method is time consuming and requires a good deal of manipulation of the framing square and addition of the table entries for the actual length of the rafter, given its pitch and run length. It can easily be seen that there are many sources of potential error in this method, namely errors in manipulating the framing square, finding the correct tables for the desired pitch, and properly reading and adding the resultant numbers from those tables.
There are at least three templates which have been designed to replace the framing square, however, one must still rely on the rafter book and the carpenter's tape to determine the necessary rafter lengths and to make the necessary measurements. In addition, the carpenter must use two different templates, or readjust the template angles, to cut all of the various types of rafters which make up the roof. U.S. Pat. Nos. 2,965,969 (Haley) and 3,183,596 (Shaw) are for a template that is fixed for a particular pitch, and 3,304,614 (Adams) discloses a template that is adjustable for various pitches. Each of these templates continue to force the carpenter to rely on the standard rafter book, while injecting another potential for error. Namely, the requirement that one template or setting be used when cutting common or jack rafters, and a second template or setting be used when cutting hip and valley rafters. By doing so there is a good chance that the wrong second template or setting for the wrong pitch could be selected resulting in lost time and waste of lumber.
It would be desirable to have a single template which incorporates the ability to make all of the rafters of a structure without the need to refer to the standard rafter book or to make extensive calculations. It would also be helpful to include with the template a tape with a scale which is expanded by a factor that corresponds to the selected pitch so that the rafters can be measured with that scale, using only the run measurement from the zero pitch roof plan without conversion to the actual rafter length.